Light emitting system, light emission control apparatus and control method therefor, communication system and control method therefor and storage medium

ABSTRACT

A light emitting system in which a light emission control apparatus wirelessly communicates with at least one controlled light emitting apparatus, the controlled light emitting apparatus comprising a first transmission unit which wirelessly transmits charging state information to the light emission control apparatus, and the light emission control apparatus comprising a receiving unit which receives the charging state information from the controlled light emitting apparatus, an informing unit which informs the image capture apparatus that a charging operation is complete, a second transmission unit which transmits a signal to stop transmitting charging state information, and a third transmission unit which transmits a light emission command to the controlled light emitting apparatus.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a technique of controlling lightemission by a light emitting apparatus.

2. Description of the Related Art

In recent wireless communication systems, it is possible to exchangevarious kinds of information by bi-directional communication. JapanesePatent Laid-Open No. 2010-259135 discloses a technique of acquiring thecharging state information of each device.

When wireless multiple flash control is performed using a plurality offlashes, for example, a user may be informed of the charging state ofeach flash using a bi-directional wireless communication system. Inwireless multiple flash control, however, it is necessary to exchangecharging state information in a shooting sequence, thereby requiringconsideration of the timing of communication in the shooting sequence.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of the aboveproblem. In controlling a light emitting apparatus, a communicationcollision is prevented to appropriately control a flash.

According to the first aspect of the present invention, there isprovided a light emitting system in which a light emission controlapparatus that is communicable with an image capture apparatus, andtransmits a light emission command to at least one other light emittingapparatus wirelessly communicates with at least one controlled lightemitting apparatus that emits light in response to a light emissioncommand from another apparatus, the controlled light emitting apparatuscomprising a first transmission unit which wirelessly transmits chargingstate information about a charging state of the controlled lightemitting apparatus itself to the light emission control apparatus, andthe light emission control apparatus comprising a receiving unit whichreceives the charging state information from the controlled lightemitting apparatus, an informing unit which informs the image captureapparatus that a charging operation is complete, a second transmissionunit which transmits, to the controlled light emitting apparatus, asignal to stop transmitting the charging state information, and a thirdtransmission unit which transmits a light emission command to thecontrolled light emitting apparatus in response to an instruction fromthe image capture apparatus, wherein if the receiving unit receives,from all controlled light emitting apparatuses, charging stateinformation indicating that a charging operation is complete, theinforming unit informs that a charging operation is complete, and thesecond transmission unit transmits a signal to stop transmittingcharging state information.

According to the second aspect of the present invention, there isprovided a light emission control apparatus which is communicable withan image capture apparatus, and wirelessly communicates with at leastone controlled light emitting apparatus for emitting light in responseto a light emission command, comprising: a receiving unit which receivescharging state information about a charging state of the controlledlight emitting apparatus from the controlled light emitting apparatus; afirst transmission unit which transmits, to the controlled lightemitting apparatus, a signal to stop transmitting charging stateinformation; and a second transmission unit which transmits a lightemission command to the controlled light emitting apparatus in responseto an instruction from the image capture apparatus, wherein if thereceiving unit receives, from all controlled light emitting apparatuses,at least charging state information indicating that a charging operationis complete, the first transmission unit transmits a signal to stoptransmitting charging state information.

According to the third aspect of the present invention, there isprovided a communication system in which a control apparatus that isconnectable with an image capture apparatus, and transmits an operationcommand to at least one controlled apparatus wirelessly communicateswith at least one controlled apparatus that executes a predeterminedoperation in response to an operation command from another apparatus,the controlled apparatus comprising a first transmission unit whichwirelessly transmits status information about a status of the controlledapparatus itself to the control apparatus, and the control apparatuscomprising a receiving unit which receives the status information fromthe controlled apparatus, an informing unit which informs the imagecapture apparatus that operation preparation is complete, a secondtransmission unit which transmits, to the controlled apparatus, a signalto stop transmitting the status information, and a third transmissionunit which transmits an operation command to the controlled apparatus inresponse to an instruction from the image capture apparatus, wherein ifthe receiving unit receives, from all controlled apparatuses, statusinformation indicating that operation preparation is complete, theinforming unit informs that operation preparation is complete, and thesecond transmission unit transmits a signal to stop transmitting thestatus information.

According to the fourth aspect of the present invention, there isprovided a method of controlling a light emission control apparatuswhich is connectable with an image capture apparatus, and wirelesslycommunicates with at least one controlled light emitting apparatus foremitting light in response to a light emission command, the methodcomprising: a receiving step of receiving charging state informationabout a charging state of the controlled light emitting apparatus fromthe controlled light emitting apparatus; a first transmission step oftransmitting, to the controlled light emitting apparatus, a signal tostop transmitting charging state information; and a second transmissionstep of transmitting a light emission command to the controlled lightemitting apparatus in response to an instruction from the image captureapparatus, wherein if at least charging state information indicatingthat a charging operation is complete is received from all controlledlight emitting apparatuses in the receiving step, a signal to stoptransmitting charging state information is transmitted in the firsttransmission step.

According to the fifth aspect of the present invention, there isprovided a control method for a communication system in which a controlapparatus that is connectable with an image capture apparatus, andtransmits an operation command to at least one controlled apparatuswirelessly communicates with at least one controlled apparatus thatexecutes a predetermined operation in response to an operation commandfrom another apparatus, the method comprising: a first transmission stepof causing the controlled apparatus to wirelessly transmit statusinformation about a status of the controlled apparatus itself to thecontrol apparatus; a receiving step of causing the control apparatus toreceive the status information from the controlled apparatus; aninforming step of causing the control apparatus to inform the imagecapture apparatus that operation preparation is complete; a secondtransmission step of causing the control apparatus to transmit, to thecontrolled apparatus, a signal to stop transmitting the statusinformation; and a third transmission step of causing the controlapparatus to transmit an operation instruction to the controlledapparatus in response to an instruction from the image captureapparatus, wherein if the control apparatus receives, from allcontrolled apparatuses in the receiving step, status informationindicating that operation preparation is complete, the image captureapparatus is informed in the informing step that operation preparationis complete, and a signal to stop transmitting the status information istransmitted in the second transmission step.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing charging state management in awireless multiple flash system;

FIG. 2 is a system block diagram showing the hardware arrangement of aflash to undergo wireless multiple flash control;

FIG. 3 is a view showing the arrangement of a camera, a master flash,and slave flashes according to the first embodiment;

FIGS. 4A and 4B are flowcharts illustrating the control operation of themaster flash according to the first embodiment;

FIGS. 5A and 5B are flowcharts illustrating the control operation of theslave flash according to the first embodiment;

FIG. 6 is a schematic view showing charging state management/lightemission control in the wireless multiple flash system;

FIG. 7 is a view showing the arrangement of cameras, a main masterflash, a sub-master flash, and slave flashes according to the secondembodiment;

FIG. 8 is a flowchart illustrating the control operation of a masterflash according to the second embodiment;

FIGS. 9A and 9B are flowcharts illustrating the control operation of themain master flash according to the second embodiment; and

FIGS. 10A and 10B are flowcharts illustrating the control operation ofthe sub-master flash according to the second embodiment.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described in detail belowwith reference to the accompanying drawings.

(First Embodiment)

FIG. 1 is a schematic view showing a flash system as an example of alight emitting system according to the first embodiment of the presentinvention. The system includes a master flash connected with a camera,and two slave flashes 1 and 2. The master flash is an example of acontrol light emitting apparatus, and the slave flash is an example of acontrolled light emitting apparatus. The master flash is connectablewith the camera, and is communicable with the camera and the slaveflashes 1 and 2. The slave flashes 1 and 2 are not directly connectablewith the camera. To inform the camera of the charging state informationof the slave flashes 1 and 2, the slave flashes 1 and 2 transmit theircharging state information to the master flash (an example of the firsttransmission operation), and then the master flash informs the camera ofthe charging state information. This is the basic outline of the systemin this embodiment.

FIG. 2 is a schematic block diagram showing the arrangement of a flash100 as an accessory of an image capture apparatus according to the firstembodiment of the present invention. Note that in addition to aso-called digital camera mainly having an image capture function, aso-called camera-equipped mobile phone and camera-equipped tablet devicemay be used as an image capture apparatus.

The flash 100 serves as a flash according to the embodiment of thepresent invention. Reference numeral 101 denotes a display/operationunit of the flash 100. The display/operation unit 101 sends an operationinstruction to a flash control unit 103 to control the flash 100.Furthermore, the display/operation unit 101 includes a shootinginstruction unit for sending a shooting instruction. When a shootingoperation is instructed, the display/operation unit 101 can transmitshooting instruction information to a master flash via a wirelesscommunication unit 105 (to be described later). Note that thedisplay/operation unit 101 is not necessarily formed by one device. Thedisplay unit and operation unit of the unit 101 may be respectivelyformed by different members such as a liquid crystal display and variousbuttons/keys, or a touch panel may serve as both the display unit andthe operation unit.

Reference numeral 102 denotes a light emitting circuit, which performscontrol operations associated with light emission such as a chargingcontrol operation and light emission control operation, and emits lightupon receiving a signal representing a light emission command from theflash control unit 103. The light emitting circuit 102 also transmits asignal representing completion of charging to the flash control unit103. The flash control unit 103 (an example of a determination unit)controls the flash with the above arrangement. The control unit alsocontrols a calculation operation for flash control or an operation ofstoring setting values. Reference numeral 104 denotes an interface withthe camera. The flash communicates with the camera via the interface104.

Reference numeral 105 denotes a wireless communication unit included inthe flash 100. There are two types of wireless communication units 105.One is a wireless communication unit 105 built into the flash 100, andthe other is a detachable wireless communication unit 105 as a separatedevice. For a separate device, assume, for example, that a card servingas the wireless communication unit 105 is used and a card slot isprovided in the flash 100. In this embodiment, the wirelesscommunication unit 105 is built in the flash. Note that a wireless LAN,Bluetooth, Zigbee, or the like can be used as a wireless communicationmethod, or other communication methods using these frequency bands maybe used. Reference numeral 105 a denotes an antenna 105 a, whichperforms wireless communication transmission/reception, and transmits,to a wireless control unit 105 b, data received from a communicationpartner. The antenna 105 a also receives data from the wireless controlunit 105 b, and transmits it to the communication partner. Referencenumeral 105 c denotes an oscillation circuit, which shapes the waveformof a clock signal generated by a crystal oscillator 105 d connected withit, and outputs the shaped clock signal to the respective circuits ofthe wireless communication unit 105, thereby synchronizing them.

FIG. 3 is a schematic view showing the system in which a flash 100A iswirelessly connected with flashes 100B and 100C. The flash 100A servesas a master flash, and the flashes 100B and 100C serve as slave flashes.A camera 200A and the flash 100A are physically connected with eachother via an accessory shoe, and perform communication via an interface104. Note that although the flash 100A is an accessory of the camera200A in the embodiment, it may be built into the camera 200A. That is,the flash 100A and the camera 200A need only have at least an interfacefor communicating with each other. Reference numerals 101A to 101Cdenote display/operation units of the flashes, which are used to makevarious settings associated with light emission or to display data; and201A, a display/operation unit of the camera, which is used to control arelease operation, make a setting of switching a camera shooting mode,and display data, and can also display the information of the slaveflashes and the like.

Although FIG. 3 shows the two slave flashes, one flash or three or moreflashes may be used.

An operation according to the first embodiment of the present inventionwill be described below with reference to FIGS. 4A, 4B,5A and 5B.

(1) Mast Flash Control

The control operation of the flash 100A serving as a master flashcommunicably connected with the camera 200A via the interface 104 willbe explained first with reference to FIGS. 4A and 4B.

In step S101, the master flash starts charging itself while transmittingcharging incompletion information to the camera via the interface 104.Charging control is managed independently of the flowchart. Uponcompletion of the charging, the charging control ends. The cameradisplays, on the display/operation unit 201A, information indicatingthat the charging operation of a multiple flash system is not complete.

In step S102, the master flash sends a state communication startinstruction to each slave flash. By receiving a state communicationsignal from each of the flashes 100B and 100C, the master flashrecognizes the network configuration of the multiple flashes. The masterflash acquires the states by receiving network information from eachslave flash (to be described later) using the wireless communicationunit 105, and recognizing the state of each slave flash in the networkof itself using the flash control unit 103.

In step S103, the master flash receives information such as chargingstate information from each slave flash. If the master flash can acquireinformation, it sets the number of slave flashes to be controlled instep S104. In step S105, the master flash determines whether thecharging operations of the slave flashes the number of which has beenset are complete. If the charging operation of at least one flash is notcomplete, the process returns to step S102 to repeat the same operationuntil the charging operations of all the flashes are completed.

If it is determined in step S105 that the charging operations of all theflashes which have been set in step S104 are complete, the processadvances to step S106. In step S106, the master flash uses the wirelesscommunication unit 105 to transmit, to each slave flash on the currentnetwork, a communication signal to stop communication of the chargingstate information (an example of the second transmission operation).With this processing, transmission of the charging state information tothe network stops.

In step S107, the master flash determines whether the charging operationof itself is complete. If the charging operation of the master flashitself is complete, the process advances to step S108; otherwise, theprocess returns to step S107 to repeat the operation until the chargingoperation of the master flash itself is completed. In this embodiment,assume that the master flash and the slave flashes emit light. Only theslave flashes, however, may emit light. If only the slave flashes emitlight, it is not necessary to execute the master flash chargingcompletion determination processing in step S107.

In step S108, the master flash informs, via the interface 104, thecamera that the charging operation of the multiple flash system iscomplete. The camera displays, on the display/operation unit 201A,information indicating that the charging operation of the multiple flashsystem is complete. The master flash also informs the slave flashes thatthe charging operation of the multiple flash system is complete.

In step S109, the master flash checks whether it has received connectioninformation from a slave flash. This is done for detecting the networkstate because it may have changed if a slave flash was powered on orsettings were changed after step S106. If a communication signal isreceived from a slave flash, the network configuration has changed, andthus the process returns to step S101 to restart checking the chargingstate of each slave flash.

In step S110, the master flash checks whether it has received a shootinginstruction from the slave flash. If the master flash has received ashooting instruction, the process advances to step S111 to transmitshooting instruction information to the camera via the interface 104;otherwise, the process advances to step S112.

In step S112, the master flash checks whether it has received a lightemission instruction from the camera. If the master flash has received alight emission instruction (an example of the third transmissionoperation), it transmits a light emission control instruction to theslave flashes using the wireless communication unit 105 in step S113. Instep S114, the master flash performs a light emission control operationby sending a light emission instruction from the flash control unit 103to the light emitting circuit 102. If the master flash has received nolight emission instruction, the process returns to step S109.

Note that in the above-described processing, the master flash does notinform the camera that the charging is complete unless the chargingoperations of all the flashes are complete. This is because if thecharging operation of at least one flash is not complete, the multipleflash system is considered not to be ready.

In the above-described processing, after the charging operations of allthe flashes are completed, the master flash transmits, to each slaveflash, an instruction to stop communication of the charging stateinformation. Some reasons for this will be described in detail below.

FIG. 6 is a schematic view showing a case in which the master flashtransmits a light emission command to each slave flash under theassumption that each slave flash regularly transmits the charging stateinformation even after the charging operation is completed. Assuming thecase in FIG. 6, the light emission command of the master flash maycollide with the charging state information of each slave flash on atransmission line, thereby causing a communication failure.

To prevent such a situation, in the processing shown in FIGS. 4A and 4B,the master flash transmits, to each slave flash, an instruction to stopcommunication of the charging state information after the chargingoperations of all the flashes are completed. In particular, timingcontrol requirements are often severe. For example, a light emissioncommand needs to be synchronous with a release operation, andretransmission processing, therefore, may be useless. To prevent acommunication collision itself, the above-described processing isexecuted.

(2) Slave Flash Control

The control operation of the flash 100B or 100C to undergo lightemission control by the master flash 100A will be described withreference to FIGS. 5A and 5B.

In step S201, the slave flash sends a connection request communicationsignal to the master flash.

In step S202, the slave flash starts charging itself while displaying,on the display/operation unit 101, information indicating that thecharging operation of the multiple flash system is not complete.Charging control is managed independently of the flowchart. Uponcompletion of the charging, the charging control ends.

In step S203, the slave flash stands by for reception of a statecommunication start instruction from the master flash. Upon receivingthe instruction, the slave flash checks its own charging stateinformation, and transmits network information and the charging stateinformation to the master flash using the wireless communication unit105 in step S204. The network information indicates a network to whichthe slave flash belongs, and is information such as an ID for provingthat the slave flash belongs to the same network. The charging stateinformation is information about charging of a capacitor for causing aflash to emit light, which may be simple information indicating whethercharging is complete, or detailed information indicating a chargingpercentage.

After transmitting the state information in step S204, the slave flashchecks in step S205 whether it has received a communication signal tostop state transmission from the master flash. If the slave flash hasreceived no communication signal, the process returns to step S203 torepeat state transmission. Note that the slave flash receives thecommunication signal from the master flash using the wirelesscommunication unit 105.

Upon receiving an information transmission stop instruction from themaster flash in step S205 (after transmission), the slave flash stopstransmitting the information to the master flash, and prepares for lightemission control so as to receive a communication signal for lightemission control.

In step S206, the slave flash determines whether it has receivedmultiple flash system charging completion information from the masterflash. If the slave flash has received the information, the processadvances to step S207; otherwise, the process returns to step S206 tostand by for transmission of multiple flash system charging completioninformation from the master flash.

In step S207, the slave flash enables the shooting instruction unit(image capture instruction unit) of the display/operation unit 101, andalso displays information indicating that the charging operation of themultiple flash system is complete. This allows the operator of the slaveflash to check the charging state of the multiple flash system.

In step S208, the slave flash determines whether it has received a statecommunication start instruction from the master flash. If the slaveflash has received no instruction, the process advances to step S209;otherwise, the process returns to step S202 to perform the controloperation again. This is done because it becomes necessary toreconstruct the network of the multiple flash system if the settings ofthe master flash or the other slave flash are changed.

In step S209, the slave flash checks whether a shooting instructionoperation has been performed through the display/operation unit 101. Ifa shooting instruction operation has been performed, the processadvances to step S210; otherwise, the process advances to step S211. Instep S210, the slave flash transmits a shooting instruction to themaster flash using the wireless communication unit 105. The master flashreceives the shooting instruction communication signal in step S110 ofFIG. 4B, and executes a predetermined operation.

After that, in step S211, the slave flash checks whether it has receiveda communication signal for a light emission instruction from the masterflash. If the slave flash has received the communication signal, in stepS212 it causes the flash control unit 103 to control the light emittingcircuit 102 based on the light emission instruction received from themaster flash.

In this embodiment, because the operation of the display/operation unit101 is always valid, a change in network state such as changing the IDor leaving the network may be instructed during the processing in stepsS201 to S211. In this case, the process returns to step S201 to performthe control operation again. By communicating a connection request withthe master flash in step S201, the slave flash causes the master flashto reconstruct the network of the multiple flash system.

With the above control method, the states of the slave flashes arerecognized and the user is informed of them. In addition, it is possibleto prevent the light emission control of the slave flashes from failingdue to a collision between shooting control communication in shootingand state acquisition communication from the slave flashes.

Furthermore, by checking the network configuration in steps S102 toS104, and repeatedly checking the network configuration in step S109even after a communication stop instruction is sent, it becomes possibleto more flexibly address the network which changes due to anincrease/decrease in number of slave flashes.

In this embodiment, upon receiving multiple flash system chargingcompletion information from the master flash in step S206, the slaveflash enables the shooting instruction unit of the display/operationunit 101 in step S207. The slave flash, however, may accept a shootinginstruction irrespective of whether it has received a communicationsignal from the master flash. That is, even if a shooting instruction issent through the display/operation unit 101 of the slave flash when themultiple flash system is in a charging incompletion state, the slaveflash transmits a shooting instruction to the master flash. In thiscase, the display/operation unit 101 of the slave flash or master flashmay display a warning that a shooting instruction has been sent when themultiple flash system is in a charging incompletion state. Furthermore,the master flash may communicate with the camera to display a warning onthe display/operation unit 201A of the camera.

Note that in addition to the wireless system including a plurality offlashes, it is possible to solely use the master flash connected withthe camera by switching the mode or the like. In this case, when thecharging operation of the master flash itself is completed, the masterflash informs the camera of it. Furthermore, the master flash need nothave a function of emitting light, and need only have a function ofcommunicating with the slave flashes to control them.

(Second Embodiment)

FIG. 7 is a schematic view showing a system in which flashes 100D and100E are wirelessly connected with flashes 100B and 100C according tothe second embodiment. The flash 100D serves as a main master flash, theflash 100E serves as a sub-master flash, and the flashes 100B and 100Cserve as slave flashes. A camera 200B and the flash 100D are physicallyinterconnected, and are communicable with each other. A camera 200C andthe flash 100E are physically interconnected, and are communicable witheach other.

The main master flash 100D can manage the network of the sub-masterflash and the slave flashes, and send a light emission instruction tothe slave flashes. The sub-master flash 100E can send a light emissioninstruction to the slave flashes.

Note that although FIG. 7 shows the one sub-master flash, a plurality ofsub-master flashes may be included. Note also that although FIG. 7 showsthe two slave flashes, one slave flash or three or more slave flashesmay be used. That is, it is possible to build a system in which one mainmaster flash, M sub-master flashes, and N slave flashes (M and N arenatural numbers of 1 or larger).

The operation of the slave flash is the same as that in the firstembodiment, and a description thereof will be omitted. The controloperations of the main master flash and sub-master flash will beexplained. An operation according to the second embodiment of thepresent invention will be described below with reference to FIGS. 8 to10.

(1) Master Flash Control

In the second embodiment, a master flash performs the operation of amain master flash or sub-master flash. Switching the operation will bedescribed with reference to FIG. 8.

A master flash transmits a connection request to a main master flash instep S301, and checks the presence/absence of a reply in step S302. Ifthe main master flash already exists, a reply to the connection requestcommunication signal is received, and this flash serves as a sub-masterflash (step S303). If no reply to the connection request communicationsignal is received, this flash serves as a main master flash (stepS304).

(1-1) Main Master Flash Control

The control operation of the main master flash will be described withreference to FIGS. 9A and 9B. In step S401, the main master flashtransmits charging incompletion information to the camera via aninterface 104, and also starts charging itself. Charging control ismanaged independently of the flowchart. Upon completion of the charging,the charging control ends. The camera displays, on a display/operationunit 201B, information indicating that the charging operation of amultiple flash system is not complete.

In step S402, the main master flash sends a state communication startinstruction to the sub-master flash and slave flashes. By receivingstate communication signals from the sub-master flash 100E and the slaveflashes 100B and 100C, the main master flash recognizes the networkconfiguration of the multiple flashes. The main master flash acquiresthe states by receiving network information from the sub-master flashand slave flashes (to be described later) using a wireless communicationunit 105, and recognizing the states of the slave flashes in the networkof itself using a flash control unit 103.

In step S403, the main master flash receives charging state informationand the like from each of the sub-master flash and slave flashes. If themain master flash can acquire information, it sets the number ofsub-master flashes and that of slave flashes to be controlled in stepS404. In step S405, the main master flash determines whether thecharging operations of the slave flashes the number of which has beenset are complete. Furthermore, the sub-master flash also transmits thecharging state information of slave flashes recognized by itself. Basedon this information, the main master flash determines whether thesub-master flash has also recognized that the charging operations of theslave flashes are complete. This is done not to advance to nextprocessing if only the main master flash recognizes that the chargingoperations of the slave flashes are complete and the sub-master flashdoes not recognize it due to a communication failure or the like.

In this embodiment, the system including the cameras and flashes hasbeen exemplified. The present invention, however, is not limited tothis, and may be applied to, for example, a system in which a pluralityof slave cameras perform an image capture operation in response to animage capture instruction from a master camera. In this case, each slavecamera transmits its status information to the master camera. When allthe slave cameras are ready to capture an image, the master camerainstructs each slave camera to stop transmission of the statusinformation.

In step S405, if the charging operation of at least one flash is notcomplete, the process returns to step S402 to repeat the same operationuntil completion of the charging operation is confirmed.

If it is determined in step S405 that the charging operations of all theslave flashes set in step S404 are complete, and the sub-master flashalso recognizes completion of the charging operations of the slaveflashes, the process advances to step S406. In step S406, the mainmaster flash uses the wireless communication unit 105 to transmit, toeach of the slave flashes and the sub-master flash on the currentnetwork, a communication signal to stop communication of the chargingstate information. This is done to prevent a collision between a lightemission command and the charging state information, as described in thefirst embodiment.

In step S407, the main master flash determines whether the chargingoperation of itself is complete. If the charging operation of the mainmaster flash itself is complete, the process advances to step S408;otherwise, the process returns to step S407 to repeat the operationuntil the charging operation of the main master flash itself iscompleted. In this embodiment, assume that the main master flash and theslave flashes emit light. Only the slave flashes, however, may emitlight. If only the slave flashes emit light, it is not necessary toexecute the main master flash charging completion determinationprocessing in step S407.

In step S408, the main master flash informs, via the interface 104, thecamera that the charging operation of the multiple flash system iscomplete. The camera displays, on the display/operation unit 201B,information indicating that the charging operation of the multiple flashsystem is complete. The main master flash also informs the slave flashesthat the charging operation of the multiple flash system is complete.

In step S409, the main master flash checks whether it has receivedconnection information from a master flash. If a new master flash isadded to the network, it sends a connection request to the main masterflash in step S301. The main master flash sends a reply, and returns theprocess to step S401 to reconstruct the network to which the sub-masterflash has been added.

In step S410, the main master flash checks whether it has received acommunication signal from a slave flash. This is done because thenetwork state may have changed if a slave flash was powered on orsettings were changed after step S406. If a slave flash has sent acommunication signal, the network configuration has changed, and thusthe process returns to step S401 to restart checking the charging statesof the slave flashes.

In step S411, the main master flash checks whether it has received ashooting instruction from the slave flash. If the main master flash hasreceived a shooting instruction, the process advances to step S412 totransmit shooting instruction information to the camera via theinterface 104; otherwise, the process advances to step S413.

In step S413, the main master flash checks whether it has received alight emission instruction from the camera. If the main master flash hasreceived a light emission instruction, it transmits a light emissioncontrol instruction to the slave flashes using the wirelesscommunication unit 105 in step S414. In step S415, the main master flashperforms a light emission control operation by sending a light emissioninstruction from the flash control unit 103 to a light emitting circuit102. If the main master flash has received no light emissioninstruction, the process returns to step S409.

(1-2) Sub-Master Flash Control

The control operation of the sub-master flash will be described withreference to FIGS. 10A and 10B. In step S501, the sub-master flashstarts charging itself while transmitting charging incompletioninformation to the camera via the interface 104. Charging control ismanaged independently of the flowchart. Upon completion of the charging,the charging control ends. The camera displays, on a display/operationunit 201C, information indicating that the charging operation of themultiple flash system is not complete.

In step S502, the sub-master flash stands by for reception of a statecommunication start instruction from the master flash. If the sub-masterflash receives the instruction, it receives information such as chargingstate information from each slave flash in step S503. If the sub-masterflash acquires the information, it sets the number of slave flashes tobe controlled in step S504. In step S505, the sub-master flashdetermines whether the charging operations of the slave flashes thenumber of which has been set are complete. In step S506, the sub-masterflash transmits a determination result to the main master flash. This isdone to inform the main master flash that the sub-master flash has alsocorrectly received charging state information from each slave flash, asdescribed above. In step S507, the sub-master flash checks whether ithas received a communication signal to stop state transmission from themain master flash. If the sub-master flash has received no communicationsignal, the process returns to step S502 to repeat the operation ofchecking the charging states of the slave flashes and that oftransmitting a determination result to the main master flash.

Upon receiving an information transmission stop instruction from themaster flash in step S507, the sub-master flash stops transmitting theinformation to the master flash, and advances the process to step S508.

In step S508, the sub-master flash determines whether the chargingoperation of itself is complete. If the charging operation of thesub-master flash itself is complete, the process advances to step S509;otherwise, the process returns to step S508 to repeat the operationuntil the charging operation of the sub-master flash itself iscompleted. This embodiment assumes that the sub-master flash and theslave flashes emit light. Only the slave flashes, however, may emitlight. If only the slave flashes emit light, it is not necessary toexecute the sub-master flash charging completion determinationprocessing in step S508.

In step S509, the sub-master flash informs, via the interface 104, thecamera that the charging operation is complete. The camera displays, onthe display/operation unit 201C, information indicating that thecharging operation of the multiple flash system is complete.

In step S510, the sub-master flash determines whether it has received astate communication start instruction from the main master flash. If thesub-master flash has received no instruction, the process advances tostep S511; otherwise, the process returns to step S501 to perform thecontrol operation again. This is done because the main master flashtransmits a state communication start instruction when the settings ofthe slave flashes are changed and it thus becomes necessary toreconstruct the network of the multiple flash system.

In step S511, the sub-master flash checks whether it has received alight emission instruction from the camera. If the sub-master flash hasreceived a light emission instruction, it transmits a light emissioncontrol communication signal to the slave flashes using the wirelesscommunication unit 105 in step S512. In step S513, the sub-master flashperforms a light emission control operation by sending a light emissioninstruction from the flash control unit 103 to a light emitting circuit102. If the sub-master flash has received no light emission instruction,the process returns to step S510.

With the above control method, the states of the slave flashes arerecognized and the user is informed of them. In addition, it is possibleto prevent the light emission control of the slave flashes from failingdue to a collision between shooting control communication in shootingand state acquisition communication from the sub-master flash and slaveflashes.

(Other Embodiments)

Aspects of the present invention can also be realized by a computer of asystem or apparatus (or devices such as a CPU or MPU) that reads out andexecutes a program recorded on a memory device to perform the functionsof the above-described embodiment(s), and by a method, the steps ofwhich are performed by a computer of a system or apparatus by, forexample, reading out and executing a program recorded on a memory deviceto perform the functions of the above-described embodiment(s). For thispurpose, the program is provided to the computer for example via anetwork or from a recording medium of various types serving as thememory device (e.g., computer-readable medium).

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application Nos.2012-020311, filed Feb. 1, 2012 and 2012-270708, filed Dec. 11, 2012,which are hereby incorporated by reference herein in their entirety.

What is claimed is:
 1. A light emitting system in which a light emissioncontrol apparatus, that is communicable with an image capture apparatus,and transmits a light emission command to at least one other lightemitting apparatus, wirelessly communicates with at least one controlledlight emitting apparatus that emits light in response to a lightemission command from another apparatus, the controlled light emittingapparatus comprising: a first transmission unit which wirelesslytransmits predetermined state information about a predetermined state ofthe controlled light emitting apparatus itself to the light emissioncontrol apparatus; and the light emission control apparatus comprising:a receiving unit which receives the predetermined state information fromthe controlled light emitting apparatus, an informing unit which informsthe image capture apparatus that a predetermined operation is complete,a second transmission unit which transmits, to the controlled lightemitting apparatus, a signal to stop transmitting the predeterminedstate information, and a third transmission unit which transmits a lightemission command to the controlled light emitting apparatus in responseto an instruction from the image capture apparatus, a fourthtransmission unit which transmits, to the controlled light emittingapparatus, an instruction to start transmitting the predetermined stateinformation, and a detection unit which detects a change in number ofcontrolled light emitting apparatuses that are communicating with thelight emission control apparatus, wherein if the receiving unitreceives, from all controlled light emitting apparatuses, thepredetermined state information indicating that a predeterminedoperation is complete, the informing unit informs that the predeterminedoperation is complete, and the second transmission unit transmits thesignal to stop transmitting the predetermined state information, andwherein upon detecting the change in number of controlled light emittingapparatuses by the detection unit after the second transmission unittransmits the signal, the fourth transmission unit transmits, to thecontrolled light emitting apparatuses, the instruction to restarttransmitting the predetermined state information.
 2. A light emissioncontrol apparatus which is communicable with an image capture apparatus,and wirelessly communicates with at least one controlled light emittingapparatus for emitting light in response to a light emission command,comprising: a receiving unit which receives predetermined stateinformation about a predetermined state of the controlled light emittingapparatus from the controlled light emitting apparatus; a firsttransmission unit which transmits, to the controlled light emittingapparatus, a signal to stop transmitting the predetermined stateinformation; a second transmission unit which transmits a light emissioncommand to the controlled light emitting apparatus in response to aninstruction from the image capture apparatus; a third transmission unitwhich transmits, to the controlled light emitting apparatus, aninstruction to start transmitting the predetermined state information;and a detection unit which detects a change in number of controlledlight emitting apparatuses that are communicating with the lightemission control apparatus, wherein if the receiving unit receives, fromall controlled light emitting apparatuses, at least predetermined stateinformation indicating that a predetermined operation is complete, thefirst transmission unit transmits the signal to stop transmitting thepredetermined state information, and wherein upon detecting a change innumber of controlled light emitting apparatuses by the detection unitafter the first transmission unit transmits the signal, the thirdtransmission unit transmits, to the controlled light emittingapparatuses, the instruction to restart transmitting the predeterminedstate information.
 3. The apparatus according to claim 2, furthercomprising: an informing unit which informs the image capture apparatusthat the predetermined operation is complete, wherein if the receivingunit receives, from all the controlled light emitting apparatuses, atleast predetermined state information indicating that the predeterminedoperation is complete, the informing unit informs that the predeterminedoperation is complete.
 4. The apparatus according to claim 3, furthercomprising: a light emitting unit, and a determination unit whichdetermines a predetermined state of the light emitting unit, wherein ifthe receiving unit receives, from all the controlled light emittingapparatuses, the predetermined state information indicating that thepredetermined operation is complete, and the determination unitdetermines that the predetermined operation of the light emitting unitis complete, the informing unit informs that the predetermined operationis complete.
 5. The apparatus according to claim 2, wherein if the imagecapture apparatus sends an instruction, the second transmission unittransmits the light emission command to the controlled light emittingapparatuses even before receiving, from all the controlled lightemitting apparatuses, at least predetermined state informationindicating that the predetermined operation is complete.
 6. Theapparatus according to claim 2, further comprising an informing unitwhich causes the image capture apparatus to display a warning if aninstruction is received from the image capture apparatus beforereceiving, from all the controlled light emitting apparatuses, at leastpredetermined state information indicating that the predeterminedoperation is complete.
 7. The apparatus according to claim 3, whereinthe informing unit informs that the predetermined operation is complete,and enables a capture image instruction in the image capture apparatus.8. The apparatus according to claim 2, wherein the light emissioncontrol apparatus is attachable to an accessory shoe of the imagecapture apparatus.
 9. The apparatus according to claim 2, wherein thelight emission control apparatus is communicable with another lightemission control apparatus, the receiving unit receives thepredetermined state information of the controlled light emittingapparatus from the controlled light emitting apparatus, and alsoreceives the predetermined state information of the controlled lightemitting apparatus from the other light emission control apparatus, andif the receiving unit receives, from all the controlled light emittingapparatuses, at least predetermined state information indicating thatthe predetermined operation is complete, and also receives, from theother light emission control apparatus, at least predetermined stateinformation indicating that the predetermined operations of all thecontrolled light emitting apparatuses are complete, the firsttransmission unit transmits the signal to stop transmitting thepredetermined state information.
 10. The apparatus according to claim 9,wherein if the receiving unit receives, from all the controlled lightemitting apparatuses, at least predetermined state informationindicating that the predetermined operation is complete, and alsoreceives, from the other light emission control apparatus, at leastpredetermined state information indicating that the predeterminedoperations of all the controlled light emitting apparatuses arecomplete, the informing unit informs that the predetermined operation iscomplete.
 11. A method of controlling a light emission control apparatuswhich is connectable with an image capture apparatus, and wirelesslycommunicates with at least one controlled light emitting apparatus foremitting light in response to a light emission command, the methodcomprising: receiving predetermined state information about apredetermined state of the controlled light emitting apparatus from thecontrolled light emitting apparatus; transmitting, to the controlledlight emitting apparatus, a signal to stop transmitting thepredetermined state information; transmitting a light emission commandto the controlled light emitting apparatus in response to an instructionfrom the image capture apparatus; transmitting, to the controlled lightemitting apparatus, an instruction to start transmitting thepredetermined state information; and detecting a change in number ofcontrolled light emitting apparatuses that are communicating with thelight emission control apparatus, wherein if at least predeterminedstate information indicating that a predetermined operation is completeis received from all controlled light emitting apparatuses in thereceiving, the signal to stop transmitting the predetermined stateinformation is transmitted, and wherein upon detecting the change innumber of controlled light emitting apparatuses in the detecting afterthe signal is transmitted, the instruction to restart transmitting thepredetermined state information is transmitted to the controlled lightemitting apparatuses.
 12. A non-transitory computer-readable storagemedium storing a program for causing a computer to function as each unitof a light emission control apparatus comprising: a receiving unit whichreceives predetermined state information about a predetermined state ofthe controlled light emitting apparatus from the controlled lightemitting apparatus; a first transmission unit which transmits, to thecontrolled light emitting apparatus, a signal to stop transmitting thepredetermined state information; a second transmission unit whichtransmits a light emission command to the controlled light emittingapparatus in response to an instruction from an image capture apparatus;a third transmission unit which transmits, to the controlled lightemitting apparatus, an instruction to start transmitting thepredetermined state information; and a detection unit which detects achange in number of controlled light emitting apparatuses that arecommunicating with the light emission control apparatus, wherein if thereceiving unit receives, from all controlled light emitting apparatuses,at least predetermined state information indicating that a predeterminedoperation is complete, the first transmission unit transmits a signal tostop transmitting the predetermined state information, and wherein upondetecting the change in number of controlled light emitting apparatusesby the detection unit after the first transmission unit transmits thesignal, the third transmission unit transmits, to the controlled lightemitting apparatuses, the instruction to restart transmitting thepredetermined state information.
 13. The apparatus according to claim 2,wherein the predetermined operation is a charging operation.
 14. Themethod according to claim 11, wherein the predetermined operation is acharging operation.